From 5febf432df1cfa5b25d99b54c32103fafbdd0eb9 Mon Sep 17 00:00:00 2001 From: Miguel Ojeda Date: Sun, 16 Aug 2026 15:32:33 +0200 Subject: kbuild: rust: keep Rust objects out of Clang LTO with inline helpers Under `CONFIG_LTO_CLANG` + `CONFIG_RUST_INLINE_HELPERS`, one may hit `objtool` errors such as: vmlinux.o: error: objtool: _R..._3Gsp4boot+0xd6a: can't find jump dest instruction at .text._R..._3Gsp4boot+0x1dfd The reason is that in such builds, the Clang invocation that compiles the combined Rust plus helpers bitcode emits LLVM bitcode (again) -- the final code generation happens in the linker's LTO step, which the `-mllvm` trap options passed to Clang do not reach. This, in turn, means that unreachable traps are missing, and the impossible paths do not merely fallthrough to the next symbol, but past the end of their own section, since LTO builds place each function in its own section. Thus filter `CC_FLAGS_LTO` out of the Clang invocation, so that it always emits machine code directly, with the traps in place. Assisted-by: LLM Cc: Gary Guo Cc: Boqun Feng Cc: Alice Ryhl Cc: Matthew Maurer Cc: Josh Poimboeuf Cc: Peter Zijlstra Cc: stable@vger.kernel.org Fixes: 3a2486cc1da5 ("kbuild: rust: provide an option to inline C helpers into Rust") Acked-by: Gary Guo Link: https://patch.msgid.link/20260816133233.197500-2-ojeda@kernel.org Signed-off-by: Miguel Ojeda --- tools/perf/util/demangle-java.c | 203 ++++++++++++++++++++++++++++++++++++++++ 1 file changed, 203 insertions(+) create mode 100644 tools/perf/util/demangle-java.c (limited to 'tools/perf/util/demangle-java.c') diff --git a/tools/perf/util/demangle-java.c b/tools/perf/util/demangle-java.c new file mode 100644 index 000000000..c3cb327ed --- /dev/null +++ b/tools/perf/util/demangle-java.c @@ -0,0 +1,203 @@ +// SPDX-License-Identifier: GPL-2.0 +#include +#include +#include +#include +#include "symbol.h" + +#include "demangle-java.h" + +#include +#include + +enum { + MODE_PREFIX = 0, + MODE_CLASS = 1, + MODE_FUNC = 2, + MODE_TYPE = 3, + MODE_CTYPE = 4, /* class arg */ +}; + +#define BASE_ENT(c, n) [c - 'A']=n +static const char *base_types['Z' - 'A' + 1] = { + BASE_ENT('B', "byte" ), + BASE_ENT('C', "char" ), + BASE_ENT('D', "double" ), + BASE_ENT('F', "float" ), + BASE_ENT('I', "int" ), + BASE_ENT('J', "long" ), + BASE_ENT('S', "short" ), + BASE_ENT('Z', "boolean" ), +}; + +/* + * demangle Java symbol between str and end positions and stores + * up to maxlen characters into buf. The parser starts in mode. + * + * Use MODE_PREFIX to process entire prototype till end position + * Use MODE_TYPE to process return type if str starts on return type char + * + * Return: + * success: buf + * error : NULL + */ +static char * +__demangle_java_sym(const char *str, const char *end, char *buf, int maxlen, int mode) +{ + int rlen = 0; + int array = 0; + int narg = 0; + const char *q; + + if (!end) + end = str + strlen(str); + + for (q = str; q != end; q++) { + + if (rlen == (maxlen - 1)) + break; + + switch (*q) { + case 'L': + if (mode == MODE_PREFIX || mode == MODE_TYPE) { + if (mode == MODE_TYPE) { + if (narg) + rlen += scnprintf(buf + rlen, maxlen - rlen, ", "); + narg++; + } + if (mode == MODE_PREFIX) + mode = MODE_CLASS; + else + mode = MODE_CTYPE; + } else + buf[rlen++] = *q; + break; + case 'B': + case 'C': + case 'D': + case 'F': + case 'I': + case 'J': + case 'S': + case 'Z': + if (mode == MODE_TYPE) { + if (narg) + rlen += scnprintf(buf + rlen, maxlen - rlen, ", "); + rlen += scnprintf(buf + rlen, maxlen - rlen, "%s", base_types[*q - 'A']); + while (array--) + rlen += scnprintf(buf + rlen, maxlen - rlen, "[]"); + array = 0; + narg++; + } else + buf[rlen++] = *q; + break; + case 'V': + if (mode == MODE_TYPE) { + rlen += scnprintf(buf + rlen, maxlen - rlen, "void"); + while (array--) + rlen += scnprintf(buf + rlen, maxlen - rlen, "[]"); + array = 0; + } else + buf[rlen++] = *q; + break; + case '[': + if (mode != MODE_TYPE) + goto error; + array++; + break; + case '(': + if (mode != MODE_FUNC) + goto error; + buf[rlen++] = *q; + mode = MODE_TYPE; + break; + case ')': + if (mode != MODE_TYPE) + goto error; + buf[rlen++] = *q; + narg = 0; + break; + case ';': + if (mode != MODE_CLASS && mode != MODE_CTYPE) + goto error; + /* safe because at least one other char to process */ + if (isalpha(*(q + 1)) && mode == MODE_CLASS) + rlen += scnprintf(buf + rlen, maxlen - rlen, "."); + if (mode == MODE_CLASS) + mode = MODE_FUNC; + else if (mode == MODE_CTYPE) + mode = MODE_TYPE; + break; + case '/': + if (mode != MODE_CLASS && mode != MODE_CTYPE) + goto error; + rlen += scnprintf(buf + rlen, maxlen - rlen, "."); + break; + default : + buf[rlen++] = *q; + } + } + buf[rlen] = '\0'; + return buf; +error: + return NULL; +} + +/* + * Demangle Java function signature (openJDK, not GCJ) + * input: + * str: string to parse. String is not modified + * flags: combination of JAVA_DEMANGLE_* flags to modify demangling + * return: + * if input can be demangled, then a newly allocated string is returned. + * if input cannot be demangled, then NULL is returned + * + * Note: caller is responsible for freeing demangled string + */ +char * +java_demangle_sym(const char *str, int flags) +{ + char *buf, *ptr; + const char *p; + size_t len, l1 = 0; + + if (!str) + return NULL; + + /* find start of return type */ + p = strrchr(str, ')'); + if (!p) + return NULL; + + /* + * expansion factor estimated to 3x + */ + len = strlen(str) * 3 + 1; + buf = malloc(len); + if (!buf) + return NULL; + + buf[0] = '\0'; + if (!(flags & JAVA_DEMANGLE_NORET)) { + /* + * get return type first + */ + ptr = __demangle_java_sym(p + 1, NULL, buf, len, MODE_TYPE); + if (!ptr) + goto error; + + /* add space between return type and function prototype */ + l1 = strlen(buf); + buf[l1++] = ' '; + } + + /* process function up to return type */ + ptr = __demangle_java_sym(str, p + 1, buf + l1, len - l1, MODE_PREFIX); + if (!ptr) + goto error; + + return buf; +error: + free(buf); + return NULL; +} -- cgit v1.3.1